It is generally believed that during economic decisions, striatal neurons represent the values associated with different actions. This hypothesis is based on studies, in which the activity of striatal neurons was measured while the subject was learning to prefer the more rewarding action. Here we show that these publications are subject to at least one of two critical confounds. First, we show that even weak temporal correlations in the neuronal data may result in an erroneous identification of action-value representations. Second, we show that experiments and analyses designed to dissociate action-value representation from the representation of other decision variables cannot do so. We suggest solutions to identifying action-value representation that are not subject to these confounds. Applying one solution to previously identified action-value neurons in the basal ganglia we fail to detect action-value representations. We conclude that the claim that striatal neurons encode action-values must await new experiments and analyses.
The data of the basal ganglia recordings from (Ito and Doya 2009) is available online at https://groups.oist.jp/ncu/data and was analyzed with permission from the authors. Motor cortex data (recorded by Oren Peles in Eilon Vaadia's lab) and auditory cortex data (taken from the recordings in (Hershenhoren, Taaseh, Antunes, & Nelken, 2014)) is available at https://github.com/lotem-elber/striatal-action-value-neurons-reconsidered-codes (Elber-Dorozko & Loewenstein 2018). The custom MATLAB scripts used to create simulated neurons and to analyze simulated and recorded neurons are also available at https://github.com/lotem-elber/striatal-action-value-neurons-reconsidered-codes.
Validation of decision-making models and analysis of decision variables in the rat basal ganglia.Publicly available at webpage of lab.
- Yonatan Loewenstein
- Yonatan Loewenstein
- Yonatan Loewenstein
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Timothy E Behrens, University of Oxford, United Kingdom
© 2018, Elber-Dorozko & Loewenstein
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Individual sensory neurons can be tuned to many stimuli, each driving unique, stimulus-relevant behaviors, and the ability of multimodal nociceptor neurons to discriminate between potentially harmful and innocuous stimuli is broadly important for organismal survival. Moreover, disruptions in the capacity to differentiate between noxious and innocuous stimuli can result in neuropathic pain. Drosophila larval class III (CIII) neurons are peripheral noxious cold nociceptors and innocuous touch mechanosensors; high levels of activation drive cold-evoked contraction (CT) behavior, while low levels of activation result in a suite of touch-associated behaviors. However, it is unknown what molecular factors underlie CIII multimodality. Here, we show that the TMEM16/anoctamins subdued and white walker (wwk; CG15270) are required for cold-evoked CT, but not for touch-associated behavior, indicating a conserved role for anoctamins in nociception. We also evidence that CIII neurons make use of atypical depolarizing chloride currents to encode cold, and that overexpression of ncc69—a fly homologue of NKCC1—results in phenotypes consistent with neuropathic sensitization, including behavioral sensitization and neuronal hyperexcitability, making Drosophila CIII neurons a candidate system for future studies of the basic mechanisms underlying neuropathic pain.
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